(CNN) -- The next time you fall sick and someone suggests it's because of something in the water, they could be right. According to the World Bank, 88 percent of all diseases are caused by unsafe drinking water, inadequate sanitation and poor hygiene.

Nanhu Lake in Chongqing, China. Around 70 percent of China's rivers and lakes are polluted.

The number are daunting. Annually, water-related problems are responsible for:

4 billion cases of diarrhea, resulting in the deaths of more than 6 million children.

300 million malaria sufferers;

200 million schistosomiasis sufferers;

6 million people who have been struck blind by trachoma;

and 500 million people who are currently at risk of contracting it, the World Bank says.

The U.N. also suggests that unsanitary water is to thank for 1.5 million cases of hepatitis A (and 133 million cases of intestinal worms).

At any one point in time, 50 percent of all people in the developing world will be in hospital suffering from one or more water-related diseases. Most will be children, water-related diseases being the second biggest killer of children worldwide (after acute respiratory diseases like Tuberculosis), according to Water Aid. (Diarrhea alone has killed more children in 10 years than all the people killed in wartime since World War 2, according to UNICEF).

Humans have become walking, talking carriers of diseases, thanks to poor sanitation and undrinkable water. Take one gram of human excrement these days, UNICEF says, and you could find around 10 million viruses, 1 million bacteria, 1,000 parasite cysts and 100 parasite eggs.

Today, 1.1 billion humans lack access to freshwater and 2.6 billion are without adequate sanitation. The World Bank says that more people have access to safe drinking water and sanitation today than they did a decade ago. The problem it says is that there are more of us now. That problem isn't going away.

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The situation in the developing world will be particularly difficult moving forward, the U.N.'s fourth Global Environment Outlook (GEO-4) is warning -- by 2025, it says, the developing world's demand for water will have increased by 50 percent (the need of developed countries will have only increased by 18 percent).

Increased demand comes at a time when freshwater stocks are falling in many places. Already in western Asia, reports The Independent, freshwater stocks have fallen from 1,700 cubic meters per person per year in the 1980s to 907 today (and by 2050 it will be just 420 cubic meters).

But access to safe drinking water is not just a poverty issue. It affects everyone. And the reason has to do with how industry disposes of its waste.

According to UNESCO, up to 500 million tons of heavy metals, solvents and toxic sludge slip into the global water supply every year. In the developing world, UNESCO says, as much as 70 percent of industrial waste is just dumped untreated into the rivers and lakes. China is a perfect case in point. According to Greenpeace, around 70 percent of China's lakes and rivers are now polluted from industrial waste, leaving 300 million people "forced to rely on polluted water supplies."

Endangered groundwater

An industry that has many fingers pointing at it, however, is the agricultural sector. Currently, the Earth's readily usable mass of potable water represents around 1 percent of the total amount of water on Earth. The vast majority of that water -- at least 70 percent -- is used for agricultural purposes. And the "main source of water pollutants in many countries" is agricultural runoff containing nutrients and agrochemicals, the GEO-4 says.

According to the Earth Day Network, 14 million people in the U.S. now regularly drink water contaminated with carcinogenic herbicides. And arsenic levels in drinking water around the globe are now putting more than 140 million people in more than 70 countries at risk of lung disease and cancers.

Arsenic is used in agriculture and is also a byproduct of coal-mining and copper smelting. It is widespread to the degree that "U.S. industries release thousands of pounds of arsenic into the environment every year," says the Natural Resources Defense Council.

According to the World Health Organization (WHO), the main agriculturally-sourced chemical contaminants in our drinking water are nitrate and pesticides, while biosolids, or sewage sludge can be a source of what is known as "excess nutrients" such as phosphorous. Excess amounts of phosphorous and nitrogen are bad news for water supplies -- namely it can cause something called eutrophication.

The U.S. Geological Survey defines eutrophication as a process where excess nutrients "stimulate excessive plant growth, often called an algal bloom [and] reduces dissolved oxygen in the water".

According to GEO-4, around 40 percent of estuaries in the U.S. are suffering from "severe eutrophication," which GEO-4 believes is so bad that it could lead to "dead zones" (where the water has effectively been starved of oxygen).

"Dead zones" are on the rise. Greenpeace says that the number of dead zones globally have doubled since 1990 to now fill up 70,000 square kilometers of the Earth's surface -- the size of Ireland.

But it's not just the rivers and lakes, however, that have become contaminated. Our groundwater supplies also are becoming polluted, according to WorldWatch Institute.

Groundwater represents 97 percent of all freshwater that is readily available to us (surface water such as rivers and lakes accounts for just 0.3 percent) Nearly one-third of all people rely "almost exclusively" on groundwater supplies for their drinking water. In the U.S, 50 percent of the population (including 99 percent of its rural population) relies on groundwater.

As time goes on, the agricultural industry globally will be required to draw on it as the demand for food grows and the available of non-polluted, non-dammed surface water areas dwindle in number.

Unfortunately, polluted groundwater is becoming more common. Already, 50 percent of groundwater samples tested by the U.S. Geological Survey contain pesticides. Arsenic contamination of groundwater has also been discovered in Argentina, Bangladesh, Chile, China, India, Mexico and Thailand, reports Earth Day Network.

According to the WorldWatch Institute, toxic chemicals have contaminated groundwater supplies "on every inhabited continent."

Struggle for cleanup money

There is one major problem with contaminated groundwater -- it takes a very long time to clean itself because water recycles slowly underground. According to WorldWatch Institute, compared to the average 16 days that water can flush out of rivers, in underground aquifers it's nearer to 1,400 years. And that effectively means that groundwater contamination as far as we are concerned, is permanent.

WorldWatch Institute says that 60 percent of "the most hazardous liquid waste in the United States -- 34 billion liters per year of solvents, heavy metals and radioactive materials" is simply pumped underground into the groundwater using what it terms as "injection wells."

Despite EPA guidelines that ensure the toxic waste goes underneath the source of drinking water, WorldWatch Institute claims that water supplies in Florida, Texas, Ohio and Oklahoma have already become infected.

One of the U.N.'s Millennium Development Goals (MDG), established in 2000 was to "halve the proportion of people without sustainable access to safe drinking water and basic sanitation" by 2015. According to the World Bank, "fewer than one in five countries are on track for meeting this target."

(Some of the ways to avert water-related deaths are simple. Washing one's hands with soap, for example, could slash diarrhea cases by nearly 50 percent and "save at least 1 million lives per year," the World Bank says.)

The reason appears to be solely to do with money -- or the lack of it. According to Make Poverty History, in 2005 only $7 billion -- less than one-third of what was required -- was committed by donor countries to the MDG relating to water and sanitation. And according to Water Aid, aid levels in general for water and sanitation are lower today than they were in 1997.

Earlier this year, special U.N. adviser Jeffrey Sachs placed the blame for the overall lack of MDG funding squarely on the shoulders of the world's richest countries, specifically the G-8, which he said that "despite endless words about increasing aid to poor countries ... are reneging on their part of the bargain."

According to Sachs, the amount of global aid actually fell by 2 percent between 2005 to 2006, once debt cancellation had been factored in. He called the amount of money needed now "miniscule."

"We are not talking about unachievable financial goals," Sachs said. "The G-8, representing nearly 1 billion people, has promised to increase aid to Africa from $25 billion in 2004 to $50 billion in 2010...To put it in perspective, the Christmas bonuses paid this year on Wall Street -- just the bonuses -- amounted to $24 billion".E-mail to a friend